clean routes

apps/website/lib/auth/PathnameInterpreter.ts

@@ -0,0 +1,97 @@
+/**
+ * PathnameInterpreter
+ * 
+ * Server-only utility for interpreting URL pathnames and extracting locale information.
+ * Strips locale prefix if present and returns the logical pathname.
+ * 
+ * Examples:
+ * - '/de/dashboard' → { locale: 'de', logicalPathname: '/dashboard' }
+ * - '/dashboard' → { locale: null, logicalPathname: '/dashboard' }
+ * - '/' → { locale: null, logicalPathname: '/' }
+ * - '/999/dashboard' → { locale: null, logicalPathname: '/999/dashboard' }
+ */
+
+export interface PathnameInterpretation {
+  locale: string | null;
+  logicalPathname: string;
+}
+
+export class PathnameInterpreter {
+  /**
+   * Interprets a pathname and extracts locale information
+   * 
+   * @param pathname - The URL pathname to interpret
+   * @returns Object with locale (if valid 2-letter code) and logical pathname
+   */
+  interpret(pathname: string): PathnameInterpretation {
+    // Handle empty path
+    if (pathname === '') {
+      return {
+        locale: null,
+        logicalPathname: '',
+      };
+    }
+    
+    // Handle root path
+    if (pathname === '/') {
+      return {
+        locale: null,
+        logicalPathname: '/',
+      };
+    }
+
+    // Normalize pathname (remove trailing slash for consistent processing)
+    const normalizedPathname = pathname.endsWith('/') && pathname.length > 1 
+      ? pathname.slice(0, -1) 
+      : pathname;
+
+    // Split into segments
+    const segments = normalizedPathname.split('/').filter(Boolean);
+
+    // No segments to process
+    if (segments.length === 0) {
+      return {
+        locale: null,
+        logicalPathname: '/',
+      };
+    }
+
+    // Check if first segment is a valid 2-letter locale code
+    const firstSegment = segments[0];
+    if (this.isValidLocale(firstSegment)) {
+      // Valid locale detected - strip it
+      const remainingSegments = segments.slice(1);
+      const logicalPathname = remainingSegments.length > 0 
+        ? '/' + remainingSegments.join('/') 
+        : '/';
+
+      return {
+        locale: firstSegment,
+        logicalPathname,
+      };
+    }
+
+    // No valid locale prefix found
+    return {
+      locale: null,
+      logicalPathname: pathname,
+    };
+  }
+
+  /**
+   * Validates if a string is a valid 2-letter locale code
+   * Must be exactly 2 lowercase letters (a-z)
+   * 
+   * @param segment - The segment to validate
+   * @returns True if valid locale code
+   */
+  private isValidLocale(segment: string): boolean {
+    // Must be exactly 2 characters
+    if (segment.length !== 2) {
+      return false;
+    }
+
+    // Must be lowercase letters only (a-z)
+    return /^[a-z]{2}$/.test(segment);
+  }
+}